Pokemon Exclusive to the Hoenn Sound feature (By Ontera)
Hoenn sound is a feature in Pokémon HeartGold and SoulSilver, active every Wednesday when you tune into your radio's music channel. Hoenn sound attracts Pokémon native to the Hoenn region. Finding and catching Pokémon exclusive to the Hoenn sound feature is done in a similar manner to catching Pokémon native to the region you are catching it in. The radio must be playing while you are in the tall grass. This means that every time you do battle, or switch to a new area, you must turn on your radio again. This is most definitely hindrance when catching rare Pokemon with the Hoenn sound.